Hubitat exposes the information needed for such a map; SmartThings does not. 
The only way to get a Zigbee map for a SmartThings network is the one you already mentioned: add a Zigbee device to your network that comes with its own mapping utilities, typically Digi XCTU. It requires some technical skill, but it’s doable.
FAQ: Mapping your ZigBee network with Digi's XCTU
Note also that generalized sniffer apps don’t give you the kind of route map that you’re looking for. They’re basically just detecting the loudness of signals nearby. They don’t show you parent and child relationships: for that, you need a mapping utility using a device which is actually participating in your network.